0=0.01x^2+0.4x+4

Solution for 0=0.01x^2+0.4x+4 equation:

0=0.01x^2+0.4x+4

We move all terms to the left:

0-(0.01x^2+0.4x+4)=0

We add all the numbers together, and all the variables

-(0.01x^2+0.4x+4)=0

We get rid of parentheses

-0.01x^2-0.4x-4=0

a = -0.01; b = -0.4; c = -4;
Δ = b2-4ac
Δ = -0.42-4·(-0.01)·(-4)
Δ = 2.7755575615629E-17
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-0.4)-\sqrt{2.7755575615629E-17}}{2*-0.01}=\frac{0.4-\sqrt{2.7755575615629E-17}}{-0.02}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.4)+\sqrt{2.7755575615629E-17}}{2*-0.01}=\frac{0.4+\sqrt{2.7755575615629E-17}}{-0.02}
$